Brothers In Arms
by Screaming Faeries
Summary: Sirius never had an entirely perfect relationship with his baby brother, but that didn't mean he didn't care about him any less. When he discovered that Regulus has been hurt, he was ready to go to the end of the earth to get his revenge. Warnings: Profanity & Drug Abuse
1. Lady Luck

**Word Count:** 1,441  
 **Written For:  
** \- Open Category 5: The Ancient & Most Noble House of Black  
\- Gringotts Prompt Bank: (street title) Cathedral Avenue, (home title) Whitemarsh Mansion

* * *

 **i  
** **Lady Luck**

"I'm going to get them for what they did to you."

Sirius was sitting on the banking by the river with his brother. The river wasn't far from where they used to live at Grimmauld Place, and it was a spot where they often used to play as children. This location acted as a comfort to both of them, despite the unusual circumstances that they had been brought back together in their early adulthood.

Regulus was looking into the water as Sirius spoke. "You don't have to," he replied awkwardly, reaching out and picking up a large, water-smoothed pebble from the sandy ground. Regulus had always loved collecting seashells and pebbles. He turned it over in his hands whilst Sirius observed him. Regulus had always been paler than the rest of the family, but he seemed more peaky than normal on that day. His skin was almost grey and translucent, and dark purple bags were prominent below his ebony eyes. Sirius reached out and tucked a lock of Regulus's hair behind his ears.

"I do," he replied quietly. "I haven't come back here for nothing."

* * *

 _Regulus had just been walking past the big old house that belonged to the Lestrange family when he first properly got talking to them. He'd never had an interest in being friends with the Lestrange brothers and their gang of miscreants before that day, but he didn't have much of a choice in the matter._

 _"Oi, Black! You're Regulus Black, aren't you?"_

 _Regulus froze on the spot where he was walking on Cathedral Avenue, and turned up to the enormous mansion. It was an ugly, grey building, with crispy brown ivy snaking up the colourless brickwork, and long, thin windows that didn't appear to let in much light. His eyes first fell on a sign by the steel gate, which read 'Whitemarsh Mansion', and then wandered to an upper floor window, where a rat-faced boy was sticking out his head. Regulus recognised the boy as Patrick Parkinson. He and his cronies were all a few years older than Regulus._

 _"Yes?"_

 _"What you doing out here on your own?"_

 _Regulus looked around, feeling slightly uncomfortable. It was often frowned upon to be having a shouted conversation through an open window—with Grimmauld Place being within a Muggle suburban, Regulus was all too used to witnessing such things._

 _"I'm just going into town," he murmured, referring to the Leaky Cauldron, where he was headed. He had planned on walking into the centre of Islington, as it was a sunny day, and then apparating to the Leaky Cauldron._

 _"What?"_

 _"Diagon Alley," Regulus called a little louder, feeling extremely stupid._

 _"What you going there for?" Regulus could hear a distinct amount of sniggering from behind Parkinson._

 _"Erm," Regulus pressed his lips together, feeling his face burning with embarrassment. "I'm meeting a friend."_

 _"Right. My mate in here says you should come in when you've seen your friend. Bring her back, if you want? We could use a few more of the ladyfolk in here."_

 _"He's a boy," Regulus croaked._

 _"Well, you come back here with him. Okay?"_

 _"Okay," Regulus had repeated, though he had no intention of stepping foot inside Whitemarsh Mansion._

* * *

Sirius had left Regulus by the river and wandered into Islington. He had hoped he would come into contact with the Lestranges and their gang.

They had hurt Regulus beyond belief. They'd humiliated him, drugged him, insulted him. They had attacked him, upset him, and worst of all—they'd left him. Left him alone to deal with the pain that they had inflicted upon him.

Sirius had never been that close to Regulus when they were children. They were siblings, and had a generic brotherly bond that was to be expected, but when they grew older and were separated when they entered Hogwarts, they soon distanced themselves from one another.

But it didn't matter how far apart they grew, or how many arguments they had. Regulus and Sirius had an unbreakable bond, and he would always go to the end of the earth for his brother. Even if that meant that he had to inflict the same kind of pain on the people who had hurt Regulus the most.

He soon found himself on Cathedral Avenue, and facing southwards, where Whitemarsh Mansion stood. Only six months had passed since Regulus had found himself inside that building, but it looked a hell of alot worse than Sirius remembered it. The concrete was crumbling, and Sirius noticed several windows had been put through and left in a state of disrepair. Since the Dark Lord had risen to power, it seemed that the once proud Lestrange family didn't care much for keeping their house in immaculate condition anymore.

Nobody appeared to be home, so Sirius continued walking until he came to a small café in the centre of the village. It was a Muggle village, so not many wizards were around, something which Sirius was glad about. More wizards meant that more people would recognise him, and he needed to make sure his alibi was clean for the next few days.

He sat down in a corner seat of the café and ordered a cup of tea, and he remained there for several hours.

Many people passed through the café. Sirius had never been interested in people watching, but he suddenly found he was fairly absorbed in observing the people that came in. Some people came in groups, and chattered and laughed for hours. Some people came in alone, like him, sitting in quiet corners of the café and sipping their tea. Couples wandered in with their fingers interlocked, having eyes for no one but each other. But it was the group of boisterous Muggle lads that were having a hushed conversation that peaked Sirius's interest.

His senses were keen due to spending a lot of time in his youth in his Animagi form, and he picked up on what the boys they were talking about. 'Getting some gear' was a common phrase that passed between them, and it didn't take a genius to work out that they were talking about drugs. It was what type of drugs that Sirius was interested in.

As if in answer, the door to the café suddenly swung open, the bell chiming loudly. A familiar rat-faced boy walked in, his skinny chest puffed out proudly. He was wearing an ill-fitting leather jacket which looked much too large for him, and obscenely tight blue jeans. A black baseball cap was perched on his head, and he wandered over to the table of boys with his hands thrust in his pockets.

He looked an eyesore. For a start, Patrick Parkinson didn't have a clue how to appropriately dress like a Muggle. The jacket he was wearing obviously belonged to Rabastan Lestrange, who Sirius remembered had a penchant for leather, and he wondered idly if Parkinson knew that the jeans were probably meant for a female. Secondly, it seemed that no-one had given Parkinson lessons on how to correctly deal drugs: with his shifty, pig-eyed squint and nervous, hunched walk, Sirius knew exactly what he was doing, and he expected that everyone else in the café did too.

Parkinson pulled something out of his pocket, and pressed it into the hand of the oldest looking Muggle. "You'll like this," he muttered. "It'll give you a good buzz. Me and the lads are calling it Lady Luck." Sirius saw a glimmer of dull gold as the tiny bottle was passed over, and Parkinson snatched a fistful of notes in payment.

It was Felix Felicis—and Sirius expected that it was poorly brewed Felix Felicis, which definitely wouldn't leave the Muggles with a 'good buzz'. He could hardly believe what he was seeing: Parkinson was distributing magical potions to Muggles, probably knowing full well that the use of wrongly brewed Felix Felicis would cause them harm, for payment.

Parkinson suddenly swung around, apparently aware that Sirius was staring at him. "You got a problem?" he asked, but Sirius didn't register that he was speaking. He was still too astounded that Parkinson would have the gall to be so stupid. "Oi! What the fuck are you looking at?"

"I'm looking at you, clearly!" snarled Sirius suddenly, causing the entire café to quieten. Parkinson flinched at Sirius's outburst, apparently not expecting such a snappy response. He backed up, span around, and exited the cafe quickly.

Sirius looked out of the window, his lips pursed. He could see that the sun was going down, creating a beautiful sunset over Islington. Soon the moon would rise, and his work could begin.

* * *

 **Please leave a review :)**


	2. The Man in the Mask

**Written For:  
** Gringott's Prompt Bank: (communal location) The Pestle & Mortar

* * *

 **ii  
** **The Man in the Mask**

Patrick Parkinson hadn't been able to shake the weird bloke out of his head since he left the café. As he sat down on the mouldy, moth-eaten couch in the Lestrange's large living room, his friends seemed to sense that something was wrong.

"What's up?" asked Rabastan Lestrange. He was leaning forward in the armchair opposite, using his deft fingers to neatly roll up a cigarette, which Parkinson knew contained a hefty amount of marijuana as well as tobacco. "You look like a ghost."

"Aw, Patty-Patty little ghosty," a shrill voice cackled from the corner of the room. In the middle of a thick cloud of smoke, Parkinson could see Bellatrix Black on the lap of her boyfriend in the sofa by the window. Rodolphus was pretty much not visible, shrouded by her plume of thick hair and the haze of smoke.

Parkinson ignored Bellatrix, turning to the two who sat in front of him. Beside Rodolphus sat Evan Rosier, who was leaning back in the chair. "Yeah, what's nagging you?"

Parkinson reached for the cigarette that Rodolphus had just rolled and handed to him, and lit it with the tip of his wand. He took a deep inhale and leaned back in his chair, staring up at the ceiling. "There was this weird guy in the Pestle & Mortar in town."

"You were dealing in that café _again?"_ interrupted Rodolphus, shooting Parkinson a glare. "Are we really going to have to discuss this again? You're going to get caught!"

"I don't think it matters!" Parkinson continued. "Anyway. So I was in the Pestle & Mortar, getting rid of Malfoy's last batch of that dodgy Felix Felicis, and he was just—staring at me."

Rosier sniggered cruelly. "You're all sweaty and shaky because some guy was _staring_ at you?"

"No, it's not just that," Parkinson continued, trying to ignore the blush that was creeping onto his face. "He was just—looking at me, you know. And it worried me, because there aren't any other wizards in Islington, other than us - and the Blacks. I didn't recognise him - at least, I didn't _think_ I did. But it's been playing on my mind all day—"

"—will you just get on with it?" snapped Rodolphus, looking impatient.

"He knew what I was doing," Parkinson went on. "I could tell. I think...I think it was Regulus's brother."

A silence fell across the room. Even Bellatrix, who had been giggling over by the window with Rodolphus, had silenced, and was looking over at the three men in the middle of the room. "Sirius Black?" she piped up suddenly. "My _cousin?"_

Parkinson nodded quietly.

"Well, what did he say?" Rodolphus pressed.

"I asked him what the hell he was looking at," Parkinson said. "I asked him twice, like—'cause he was just staring, right weirdly. And he just—I don't know, he just snapped. Screamed that he was obviously staring at me, or something. It freaked me out."

"Regulus's brother," repeated Rosier slowly, his attention focusing back on the ceiling.

* * *

 _Parkinson had seen Regulus trying to sneak back to Grimmauld Square through the hedges at the end of the avenue. He stuck his head back through the window again, trying to get a better look at the youngest Black brother and the friend who was following him. "Hey! Hey, Regulus!"_

 _Regulus jerked back from the hedge so quickly that he bumped into his skinny, sandy-haired friend. The pair of them struggled to regain composure, and Parkinson laughed loudly, trying to signal for his friends to come and have a look. Rodolphus, Rabastan and Evan Rosier seemed completely uncaring about the boys outside._

" _Hi," Regulus greeted quietly, his voice almost inaudible._

" _Are you coming in then? Who's your friend?" Parkinson pressed._

 _Regulus and his friend edged a little closer to Whitemarsh Mansion, but their eyes were shooting back to the gap in the hedge where they had planned on climbing through. "This is Barty Crouch," mumbled Regulus._

" _Barty Crouch!" bellowed Rabastan suddenly, jumping up to the window and shoving Parkinson out of the way. "Well if it isn't the son of the man who put our father in Azkaban!"_

" _Regulus, we should_ — _" Barty hissed, but Rabastan wasn't having any of it._

" _No, come in boys. Come on_ — _it's okay! Bellatrix, go get them." Rabastan muttered, and Bellatrix rolled her eyes and climbed up from the sofa, before stalking out of the living room. Within a few moments, she had appeared on the front path, and was stalking towards the two younger boys. She took each of them by the arm and dragged them into the house._

 _Her leering smirk didn't go unnoticed by the rest of the gang in the house._

 _When she had dragged them both up into the living room, Rabastan proceeded to shove Regulus onto the couch and then drag Barty out of the room, shutting the door behind him. Regulus looked extremely uncomfortable without his friend, so Bellatrix slid onto the couch beside him, putting an arm over his shoulders._

" _What's up, little 'cuz?" she purred, but she was eyeing Rodolphus. "Do you want something to loosen you up?"_

" _No, it's okay," Regulus stammered nervously, his bottom lip quivering. "To be honest, Barty and I really should_ — _Barty!"_

" _Rabastan's just having a chat with him," Rodolphus muttered, and sat in the seat on Regulus's other side. "Here_ — _have a bit of this." Rodolphus had pressed a tiny glass vial of purple liquid into Regulus's hand, and he took a tentative sniff of the unnamed potion._

" _What is it?"_

" _That doesn't matter. Just drink it." Parkinson could see that Regulus was trying to work out if he recognised the contents of the potion, but to no avail._

" _I don't think I_ — _"_

" _Just fucking drink it, Regulus!" hissed Bellatrix, and she grabbed the back of her cousin's hair roughly, forcing him to tip his head back, and used her other hand to prise open his bottom jaw. Rodolphus grabbed his flailing arms, and Parkinson quickly snatched the potion, unscrewing the cork and tipping it into Regulus's open mouth._

* * *

The sky outside was dark when Parkinson finally decided that he was sober enough to leave the Lestrange's drug nest and head home to where he lived in East Barnet. He climbed up from the sofa, ignoring the mass of sleeping bodies around him, and quietly edged out of the living room.

He was at the glass front door when something stopped him in his tracks.

There was a figure behind the door. A tall, intimidating figure dressed entirely in black, and with a black balaclava pulled over his face. His dark eyes were glowering through the glass at Parkinson.

Still slightly stoned, Parkinson laughed. Obviously this was some kind of joke—Halloween was coming up, and it wasn't unusual for the kids around the Muggle area to try and get sweets early. Unlike Grimmauld Place, Whitemarsh Mansion didn't have any protective enchantments around it to hide it from Muggles. Generally, the Muggle onlookers were naturally intimidated by the exterior.

"Yeah, nice gag, mate," Parkinson called through the window. "Can you fuck off now though please, so I can come out?"

The masked figure beckoned his finger silently, gesturing for Parkinson to exit the house and face him. But Parkinson was a coward, so he strained a grin, and shook his head.

"Get out here now!" growled the masked man suddenly, and Parkinson nearly jumped out of his skin. He backed away from the door, shooting back upstairs to the living room where his friends were.

"Get up!" he screamed. "Get up, quick!" he grabbed Rabastan by the arm, and he sat up groggily.

"What the fuck is wrong with you?" Rosier snarled from his curled position on the floor. He pulled himself to a seating position and dug his knuckles into his eyes.

"There's some—bloody _maniac_ outside! Banging on the door like a madman-got a bloody—balaclava, or something—"

"He's still fucked," muttered Rodolphus. Bellatrix murmured on the armchair beside him, apparantly undisturbed by the racket.

"I'm serious!" Parkinson yelled, and Rabastan rolled his eyes.

"Fine, for fucks sake," he muttered, and he followed Parkinson out of the living room, followed by Rosier and Rodolphus. The four men rushed downstairs and out of the door, dashing out onto the front lawn.

They paused in the quiet night air, looking around. "There's no one here, you idiot!" yelled Rodolphus, and Rabastan slapped Parkinson up the head as they passed him to get back into the house.

Once they had got back inside to the living room, they all sat back down on their respective seats. But there was something amiss.

Parkinson looked around the room slowly. It had been trashed—it was even more a mess than usual. The lamp in the corner had been overturned, and a rubbish bag had been emptied around the room. On inspection, Rodolphus noticed that the intruder had scribbled on Bellatrix's face: the word 'whore' was written in marker pen across her forehead.

But that wasn't all.

Parkinson looked at the coffee table, where he had previously left three small, unopened bottles of Lady Luck - the dodgy, improperly brewed version of Felix Felicis. They were gone. "Malfoy's gonna kill me," he groaned, reaching up and grabbing his hair.

"What?" Rodolphus asked, turning his attention to Parkinson. "Why?"

"The...the last bit of Felix was on the bloody table. It's gone."


	3. Fear The Reaper

**Word Count:** 1,187

* * *

 **iii  
Fear The Reaper**

Sirius flicked the tab end of his cigarette to the curb as a large silver car screeched to a halt beside him. A little further up the path, Regulus stood by a wall, chewing on a hangnail. There was a worried look in his eye, but Sirius grinned at him confidently.

The window of the large Rolls Royce slowly wound down, and a familiar man with long, dark hair and heavy stubble glared out at him. It was Rabastan Lestrange.

"My friend wants a word with you," he told Sirius sternly, and Sirius cocked an eyebrow, the grin still spread on his features. The back door of the car clicked and swung open, and a cane slammed against the pavement, followed by a tall, slender man with ice-blonde hair, which was tied back at the nape of his neck. He leered at Sirius as he gently closed the car door and walked over to Sirius.

"Someone has been sneaking around Whitemarsh Mansion," sneered Lucius in a quiet voice, pressing his lips together firmly once the words had left his mouth. "I wondered if perhaps you might know something about that."

"Yeah, it was me," Sirius replied, scratching the back of his head.

"Oh, well I'm glad we could agree on something." Lucius unscrewed the handle of his cane, and unleashed his wand. "You see, you took something of mine. A few vials of potion. I'd like those back, if you will."

"No can do, mate."

"Well," Lucius began to hiss an incantation, and raised his voice. However, Sirius was too quick for him. He ducked under Lucius's raised arm, and slammed the blonde man into the wall that he had previously been leaning against. It only took one small twist of his arm, and Lucius had dropped his wand, and Sirius kicked it up the path.

"You get two hours," Sirius snarled into Lucius's ear. "Two hours before it begins."

As Lucius stood with his face pressed against the brick, he began to regret even more what they had done to Regulus.

* * *

 _Regulus's vision was swimming as he listened to the voices and the laughter around him. The door to the living room opened with a loud creak, and a tall blonde man entered, wearing a tight-collared suit. He unfastened his tie as he sat down opposite Regulus._

" _What is that brat doing in here?" he demanded to know, looking over at Parkinson. Parkinson shrugged._

" _Rabastan thought it would be fun if they came in."_

" _They?" Lucius repeated. "Who is 'they'? And where is Rabastan?"_

 _As if on cue, the living room door opened again, and the Barty Crouch Junior was pushed through. His hair looked ruffled and his eyes were red and puffy, as though he'd been crying. Rabastan followed after the boy, a dark smirk on his face. He was zipping up the front of his jeans as he entered the room._

" _Why do you smell of sweat and shame?" Lucius questioned as Rabastan sat down beside him._

" _I thank you to mind your own business, Malfoy," replied Rabastan with a grin. He grabbed Barty by the sleeve and yanked him down onto the couch, where he fell uncomfortably into the small gap between Rabastan and the arm. Regulus stared desperately over at his best friend, his eyes wide and apologetic._

" _What did you do to him?" he croaked, his lip shuddering. Rabastan smirked._

" _I'm sure you'll be able to talk about that later."_

" _I've had enough of this" snapped Lucius, and he stood up sharply. "You are all hanging around in this once proud mansion, sitting in your own filth. Look at the state of you all! Rabastan, Rodolphus—if your parents could see you now. And Bellatrix! Your father would be_ appalled _if he knew what you were getting yourself into."_

 _From her position on Rodolphus's lap, Bellatrix stuck out her tongue and sniggered. Lucius rolled his eyes, and allowed his glance to fall on Regulus._

" _And you," he sneered, looking down the length of his long nose at the younger boy. "The progeny and future of the House of Black. What any other man in this room wouldn't give to be you."_

 _Regulus swallowed, blinking up at Lucius with his foggy gaze._

" _What it must be like to be you; the only son of this generation of Blacks, responsible for leading the purest of wizards into the twenty-first century?"_

" _I'm not an only son. Sirius—"_

"— _Doesn't exist," Lucius interjected sharply. "Ever since he ran off to the Potters. And look at the state of you—it's no surprise the boy decided to abandon his blood. Here he is, little baby Black, squatting in this squalor."_

" _I don't want to be here," Regulus whispered hoarsely. "I want to_ go. _"_

" _Silence," scoffed Lucius. "Yes, what Mummy would say if she could see you right now, out of your mind on drugs. You know, I could have a word with her." Bellatrix looked up at this, glaring over at Lucius, but he gave her a knowing smirk. Regulus didn't notice this, and continued to gaze up at the blond fearfully._

" _Please," he begged. "Please, don't tell her..."_

" _Follow me into the kitchen," Lucius ordered. "Lets see what I can do."_

* * *

Sirius glanced up the pathway, to where Regulus was standing out of the way of the confrontation. His younger brother was shuffling his feet, staring down at the ground. Sirius turned back to Lucius, and shoved him back towards the Rolls Royce.

"Get out of here," he snapped.

"Where are you staying?" Lucius asked suddenly, his eyes glittering.

Sirius smirked. "Brixton Hill," he replied. "Above the Costcutter's. Why, are you going to come and pay me a visit?"

Lucius raised an eyebrow. "I might."

Sirius nodded, never breaking eye contact. "In Brixton? Bit rough for you, when you were brought up in _—_ Wiltshire, isn't it?" His smirk intensified.

"You're not afraid of me, are you?" Lucius questioned.

"Not even a bit. Now go and get back in that car," Sirius ordered, gesturing towards the Rolls Royce. Lucius turned on his heel slowly, and walked back towards the car. He slid into the front seat, and offered Sirius one last glare, before driving away.

* * *

 **A.N:** Apologies for any mistakes! I couldn't manage to get a beta. Please R &R :)


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